Telephone system



4 Sheets-Sheet 1 Aug. 1, 1939. w. PFAFF TELEFHONE SYSTEM Filed Feb. 17,1937 Aug. 1, 1939. w. PFAFF 2,167,725

y TELEPHONE' SYSTEM ,f

Filed Feb. 17, 19:57 4 sheets-sheet 2 INVENTOK WALTER PFAFF ATTORNEY.

Aug. 1, 1939. w. PFAFF Y TELEPHONE SYSTEM Filed Feb. 17, 1957 4Sheets-Sheet 5 ATTORNEY.

Aug. l, 1939. w. PFAFF TELEPHONE SYSTEM fi 4 Sheets-sheet 4 Filed Feb.17, 1957 www@ Naw.

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INVENT OR. WALTER PFA FF ATTORNEY.

Patented Aug. l, 1939 TELEPHONE SYSTEM Walter Pfaff, Berlin-Zehlendorf,Germanrls- A signor to Siemens & Halske Aktiengesellschaft,

, Wernerwerk, Siemen many application February 17, 1931, semi N0.126,163

In Germany March 6, 1936 Y l 1g claims. I'he invention relates to acircuit arrangement for call'indicating systems in association with.

telephone systems and aims at avoiding the withdrawal of the telephonesystem connecting path from the traffic when connection is establishedbetween the party who is sought and the call indicating system. 'I'hisis achieved by the present invention in that the sought party causes aswitch associated with the call indicating system to be set on-the lineof the station from which he replies while simultaneously releasing theswitches of the telephone system after a reply signal has been given.

The drawings comprising Figs. 1A, 1B, 2A and 2B show an embodiment ofthe invention. 'I'hey represent a private branch exchange system inassociation with a call indicating system. It may occur that asubscriber who is busy cannot answer a telephone call or that a visitordoes not nd the desired person at his desk. In either case the seekingparty can cause a special call indicating signal to be operated atvarious points in the works.` The desired party can then estalolshconnection to the calling party over the reply line after giving aspecial signal from the nearest equipment.

The individual switching operations are as follows:

When the seeking party at the station Tnl in Fig. lA takes up lthereceiver the call nder lil AS is set on the calling party in the knownway. .citer the call finder has been set the testing re-A lay Cenergizes over wiper c of the call iinder AS and switches through thespeaking leads at contacts ic and 2c. A feeding circuit is set up overrelays AI and XI. The dileren'tial relay Xi does not energize. When thecallingparty transmits a particular searching digit the iinal selectorLW is set on a particular contact whereupon the following circuit is setup: positive, relay P, wiper c, lead 3 in Figs. 1A, 1B and 2A, winding Iof relay Rl, contacts .4c2 and "tr, winding III of relay Tr andnegative. In this circuit relays `l`P, RI and Tr energize. Relay Rl setsup the following circuit: positive, contacts 5c2, Srl and lu2, rotarymagnet DSW and negative. 'I'he rotary magnet DSW advances the switch SW.Over the following circuit: positive, contact dsw, windingI of relay UIand negative, relay UI is energized. Relay UI at contact Sul completes acircuit for relay U2. Relay U2 opens contact lu2 and thereby breaks thecircuit for the magnet DSW. At contact dsw the circuit for relay UI isopened and the latter releases and by opening contact Sul resstiult,near Berlin, Ger- (cl. 17e-1s) leases relay U2. 'I'he circuit over therotary magnet DSW ls again setup over vcontact. 'lul so that the switchSW takes a further step forward. The rotary magnet DSW and the relays Uland U2 operate together in the manner described un- 5 til the followingcircnit'becomes established over wiper d of the switch SW: positive.contact Ilvl, winding l1 of relay C2, contact Ilrl, wiper d of switchSW, lead l2 in Figs. 2A, 1B and 1A, wiper d of can finder as, Contactup, remy Hr, wiper :loV

d of the iinal selector LW, lead il, resistance WE and negative. In thiscircuit relay C2 in Fig. 2A energizes and opens contact 5c2 in thecircuit for rotary magnet DSW. The switch SW is accordingly brought torest. The guarding l5 circuit is prepared over contact i602.

The relay I-IT energizes over the circuit over wiper dof switch SW andreleases the hnal selector LW in the known manner (not shown) and also,releases the call nder AS. The known 20 guarding eilect over wiper c ofcall nder AS neutralized so that now the following i' circuit over wiperc of switch SW in Fig. 2A ca be set up: positive, contacts |662 andl'ltr, winding I of relay C2, wiper c of switch SW, lead il 25 in Figs.2A, 1B and 1A, relay TI and negative.

The energizing of relay C! causes the line to be switched through atcontactsV isc! and No2. Thus the following circuit is established forthe calling party: negative, winding I or relay Si, winding I of relayX2, contact l9c2, wiper u of switch SW, lead 22 in Figs. 2A, lB and l,over the loop at station Tnl, lead 2l in Figs. lA, 1B and 2A, wiper l)of switch SW, Contact 201:2, winding II of relay X2, winding ll'. cirelay Si, and positive. Only relay Sl energiaes in the above circuit.Relay X2 is a. ldierental relay. Over contact 23sl relay VI is energizedand breaks the short-circuit for winding I of relay C2 at contactsv2411i when contact 251| is closed after relay RI is released. Therelease of relays RI and Tr takes place when relay C2 energizes. RelayC2 opens contact c2 and closes contact 26c2. 'I'he following circuit isset up over relay V: positive, contact 3Ic2, winding III of relay V,wiper e of the switch DI in position 0, rotary magnet DMI, winding I ofrelay V and negative. In this circuit only relay V energizes; the rotarymagnet DMI is not operated.

The calling party now dials the digit for con- 50 necting'up aparticular calling signal.

It is assumed that the characterizing number for the desired party isthe digit 6. In this case according to the embodiment the acousticsignal for the desired party consists of two short signals .5

followed by a long signal. Lamps LI and L3 are operated to constitute avisible signal.

'I'he impulse train of six impulses transmitted by the calling party istaken' up by relay SI in Fig. 2A yand in Fig. 2B is repeated by contact2`|s| to the rotary magnet DMI of switch DI. 'I'he circuit of the rotarymagnet DMI passes over positive, contacts 28D, 2312, 3011i, and 213|,rotary magnet DMI, winding I of` relay IV and negative. Relay V remainsenergized throughout the impulse train. When relay V falls back at theend of the train and the wipers of switch DI are in position 6 thefollowing circuit is established over wiper a of switch DI: negative,contact 3211. wiper a of switch DI in position 6, lead 33, lamp LI andpositive. Over wiper b of the switch DI the following circuit isestablished: negative, resistance W, contact 34D, wiper b, in position8, lead 3l, lamp L3 and positive. Thus the lamps L| and L3 light up.Wiper c of switch DI is also set inr position 8 and is accordinglyprepared for connecting up of an acoustic signal.

When relay V releases after the impulse train the following circuit isset up for rotary magnet DM2: positive, contacts 3611.2, 310|, 681'2 and3811, rotary magnet DM2 and negative. The rotary magnet DM2 advances thewipers of switch D2 one step and by closing contact 33dm2 in Fig. 2Acauses relay UI to be energized over positive, contact 39dm2, winding Iof relay UI and negative. Relay U2 is energized over contact Sul. InFig. 2B, over the windings II of relays UI and U2 and contacts 4312,44s|, 451'2 and 461L2 a damping circuit is established soothat relays UIand U2 operate and release slowly and thus cause the switch D2 to bestepped slowly by the rotary magnet DM2. At contact 36u! relay U2 breaksa circuit for magnet DM2. Contact 39dm2 is opened and relay UI releases.At contact 3u| the circuit is broken for relay U2 so that the circuitfor magnet DM2 is again established over contact 361L2. Magnet DM2operates with relays UI and U2 as an interrupter so that the switch D2is advanced until the called subscriber replies. When wiper c of switchD2 reaches contacts 8, 8, i0, and I2 the following circuit isestablished: positive, contact 40u, wiper c of switch DI in position 8,contacts 8, 8, I0, or I2, wiper c of switch D2 contact 48tr, and lead 4|over the bells at various positions in the works to negative. Inrotating wiper c bridges adjacent contacts, so that ringing is notinterrupted as the wiper passes over contacts l0, and I2, and the bellsare thus rung in two short pulses followed by one long pulse. When thewanted party becomes aware of the signal which is individual to him heproceeds to the nearest telephone set. It will be assumed that hereplies from the station Tn2 shown in Fig. 1A. When the receiver hasbeen removed the call finder AS is set on the calling line. After thecall finder has been setl the wanted party transmits a special relaydigit whereby the final selector LW of the telephone system is set on aparticular contact.

On account of this setting of the final selector LW the followingcircuit is set up over the test wiper c of the final selector LW:positive, test relay P, wiper c of the nal selector LW, lead 42 in Figs.1A, 1B and 2A, relay R2, contacts 26c2, 41tr, winding III of relay Trand negative.

Relay Tr opens contacts IItr and 41tr. Winding II of relay Tr wasshort-circuited so that relay Tr was made slow to operate. Shortlybefore relay Tr energizes relay R2 energizes. Conthe tact 481'2 closesso that the guarding circuit passes over winding I of relay C2 andcontacts f2 and |8c2.y Relay R2 opens contact r2 and prevents furtheroperation of the rotary magnet DM2. On

account of contact 4312 being opened the damping circuit for windings IIof relays UI and U2 cannot be established when the switch MW is beingset and consequently this switch is stepped rapidly. Relay'Tr also openscontact tr in Fig. 1A and closes contact Il tr so that a callingsubscriber cannot start up a public exchange switch by dialling thecharacterizing digit for outgoing calls. Moreover, the switch MW in Fig.-2A is prevented from testing on a calling subscriber who has dialledthe public exchange characterizing digit.

Relay R2 in Fig. 2A also closes contact 52r2 so that the rotary magnetDMW is energized over the following path: positive, contacts 53c3,521'2, 54u2, rotary magnet DMW and negative. Magnet DMW closes contactSSdmw so that relay UI is energized. Relay UI closes the circuit forrelay U2 over contact Sul. Relay U2 energizes and at contact 54112breaks the circuit for the rotary magnet DMW. Magnet DMW restorescontact 55dmw to normal. Relay UI releases so that contact 3u| is openedand thus a circuit for relay U2 is broken. Relay U2 again completes thecircuit for magnet DMW over contact 54u2. Magnet DMW is operatedtogether with relays UI and U2 until the following testing circuit isestablished: positive, contact 560| winding II of relay C3, contact511'2, wiper d of switch MW, lead 58 in Figs. 2A, 1B and 1A, wiper d ofcall finder AS, contact |3p, relay HT wiper d of final selector LW, lead53, resistance W2 and negative. In this circuit relay C3 in Fig. 2Aenergizes. By opening contact 53c3, relay C3 brings the switch MW torest and at contact 6803 prepares the guarding circuit over wiper c ofthe switch MW. Relay HT energizes in the testing circuit over lead 58and wiper.

d of the call finder AS and promotes the release of the final selectorand of the call finder AS in the known way. On account of the release ofthe final selector the circuit over wiper c of this switch and lead 42in Figs. 1A, 1B and 2A is broken. Relays R2 and Tr release. Relay Tr alease of relay Tr the following guarding circuit is established overwiper c of switch MW: positive, contacts 60c3, Mtr and 6212i, winding Iof relay C3, wiper c of switch MW, lead 63 in Figs. 2A, 1B and 1A, relayT2 and negative. The following feeding circuit is now established forthe wanted party: negative, winding I of relay SI in Fig. 2A, winding Iof relay X2, wiper a of switch MW, lead 64 in Figs. 2A, 1B and 1A overthe loop at station Tn2, lead 65 in Figs. 1A, 1B and 2A, wiper b ofswitch MW, winding II of relay, X2 winding II of relay SI and positive.

I'he calling party at station T1l| and the wanted party who has repliedfrom station T112 are now connected together over the switches SW and MWin Fig. 2A.

When the subscribers have conversed together and have both replacedtheir receivers the feeding bridge relay SI falls back. Relay SI breaksthe circuit for relay V| at contact 233|. 'I'he rotary magnet DM2 issubjected to current over:

positive, contacts 38u! and 3lv|, wiper e of switch 7 position and thecircuit for the rotary magnet DM2 over wiper e of switch D2 can nolonger be set up. When the switch D2 is in the normal position switch DIis restored to normal in that the following circuit is set up for magnetDMI: positive, contacts 68c2, wiper d of switch D2 in the rest position.contact 50112, wiper e of switch DI in the working position, rotarymagnet DMI,

winding I of relay V and negative. Magnet DMI closes contact |dml sothat relay UI is energized over: positive, contacts IIvI and 10dmI,winding I of relayiU| and' negative. Relays-UI Y and U2 now :operatetogether with magnet rDMI until wiper e of switch DI has reached thenormal: po-

sition. Whensthis .-has` occurredLthecircuitffor magnet DMI overwiper eis no longer established. l

Thus all thefdevices which-have been.. taken into use are onceinore inlthen'ormalposltion.

It is possible also for a subscriber connected to the exchange line ALto seize the devices of the call indicating system over the enquiry pathif the party called in anenquiry call is absent from his position andaccordingly does not reply.

An outgoing public exchange call is set up in the following way. Afterthe receiver has been removed and the call finder AS has been set on thecalling line the subscriber has to dial the digit characterizingoutgoing public exchange calls. The following circuit is then set upover wiper c: positive, testing relay P, wiper c of the final selectorLW, lead 12, contacts 50tr and 13b, winding I of relay R and negative.It should be noted that when there is a free public exchange line relayB is energized over: positive, contact 840| or 85s, contacts 86h,winding of relay B, contact 80h and negative, and its contacts assumethe position shown inthe drawing. Relay R closes contacts 'I4r and '|5r.Contact 141' closes the circuitfor the rotary magnet DAW. The circuitVpasses over positive, relay interrupter RU. contacts 16c| and 141,rotary magnet DAW and negative. The public exchange switch AW is steppedby the rotary magnet DAW until the following testing circuit isestablished: positive, contacts I'Iab abd Tir, winding II of relay CI,wiper d of the public exchange switch AW, lead I2, wiper d of callfinder AS, contact |3p, relay HT. wiper d of the final selector LW,contacts 18h and |5ab, resistance WI and negative. In this circuit relayCI energizes and brings the switch to rest by opening contact 160|.Relay HT brings about the release 'of the final selector LW and of thecall nder AS in the known man-l ner (not shown). 'I'he followingguarding circuit is now established: positive, contacts 19u, 80122, andB|c| winding I of relay CI, wiper c of the public exchange switch AWlead I8, relay TI and negative. Relay CI switches through at contacts82c| and 830|. T'he feed bridge relay S is energized and opens contact85s. The circuit for relay B is broken by the opening of contact 85s.Relay B opens contact 86h and closes contact 81h. At the same timecontact 13b has opened and contact 89h closed. Relay R falls back and afurther impulse for setting a public exchange switch is transmitted overcontact 89h 'to a. second public exchange switch.

Relay S switches through at contact 90s. The calling subscribed is thusconnected with the public exchange line AL.

An incoming public exchange call is established in the following way.-Relay A is energized by the ringing current flowing over the exchangeline. Relay A establishes a circuit for relay H over: positive, contactSI1', winding I of relay H,

contacts 92a and 92h and negative. locks up over contact 84c| or 05s,contact 94123, winding II of relay H, contact h and negative. Relay Hestablishes the following circuit: positive, contact 96h, windings IIand I of relay C|,` wiper c of the public exchange switch AW in thenormal position, lead 91, lead I8, relay TI and negative. Switchingthrough is effected at contacts 82c| and 83c| by relay CI, while windingII of relay. CI is short-circuited by contact 8|c| and thus the line ofsubscriber TnI -is guarded in the known way. The following ringingcircuit is set upzfffrom thevsour'ce RQ of ringingcurrent over contact08h, winding I of relay S, winding IV of relay X, 'winding I of repeaterUe', contact 82cI, wiper a of the public exchange switch AW, lead 99,lead 22, to bell at station TnI, lead Relay H 2|, lead |00, wiper b ofthe exchange switch AW in the normal position, contact 83cI, winding 1Iof repeater Ue, winding II of relay X, winding II of relay S andpositive.

When the subscriber at station Tnl takes up the receiver relay Senergizes. Relay S breaks the locking circuit for relay H and thecircuit for relay B at contact 85s. Relay B releases and at contact 93hbreaks the circuit for winding I of relay H. Relay H restores itscontacts to normal. Current is fed to the called subscriber over contactIOIh.

After the switching through at contact 90s the calling public exchangesubscriber is connected to the subscriber at Tnl. If now the exchangecall is to be extended to another subscriber the subscriber at station'I'nl promotes the establishment of an enquiry call. As a result of thetransitory depression of key Tal the differential relay X disposed inthe feeding circuit is energized and establishes the following circuit;positive, contacts |02c| and |0332, winding I of relay Z, contact |0411,resistance W4 and negative. Relay Z energizes and closes contact |052.When the key is released relay X falls back and contact I 03a: isopened. The following circuit is established: positive, contact I02cI,winding Il of relay Y, contact l05z, winding II of relay Z, winding I ofrelay Z, contact |0411, resistance W4 and negative. In this circuitrelay Y is also energized and opens contact |04y and closes contact I25g.

y The following circuit now obtains for relays Y and Z: positive,contact |02c|;,winding II of relay Y, contact |05z, winding II of relayZ, contact |2511, winding I of relay Y and negative. Relay Y establishesa holding bridge across the leads of the public exchange line overcontact |053/ and resistance W5. Relay Y by opening contacts |06y andI0'Iy and closing contacts |081/ and |09@ causes the public exchangeline AL to be switched over on to the enquiry line I|0/||I. 'I'he callfinder AS is caused to be set on the enquiry line ||0/ by the loop overcontacts |083/ and 90s, windings IV and III of the repeater Ue andcontact |09y. After the call finder AS has been set impulses aretransmitted for setting the final selector LW. The impulses are receivedby relay S and are repeated over the enquiry line ||0/||| by Contact 90sto relay A| in the final selector LW. If the final selector is set onthe line of a subscriber who does not reply the enquiring party switchesback on to the public exchange line. This is effected by againtransitorily depressing the key. The diiferential relay X in the feedingcircuit of subscriber Tn| is energized and short-circuits Winding II ofrelay Y and Z at contact |0332. Relay Z accordingly releases and openscontact |052. When a subscriber releases the key Tal relay X releasesand contact |031: opens again. Relay -Y releases and switches back fromthe enquiry line on to the exchange line by opening contacts Illu andIlly and closing contacts Iliy and Illy. f

'Ihe subscriber at the calling station again causes the public exchangeline to be switched over to the enquiry line in the manner alreadydescribed. After this has been eiiected the characteristic digit for thecall indicating device has to be dialled. The circuit for relays RI andTr is set up over wiper e of the ilnal selector LW and lead 3 in Figs.1A, 1B and 2A. Relay RI causes the switch SW to be set in the manneralready described. The switch SW is brought to rest when the followingcircuit is established: positive, contact lllvl, winding II of relay C2,contact lirl, wiper d of switch SW, lead |12 in Figs. 2A, 1B and 1A,wiper d of the call ilnder AS, Contact |312, relay HT, wiper d of thefinal selector LW. lead I4, resistance W6 and negative. The switch SW isthus set on the enquiry line ||0/||I. Relay CI eiects the switchingoperations already described such as guarding and switching throughwhile relay HT releases the nal selector LW and the call iinder'AS whichhas been set on the enquiry line. The subscriber at station Tnl nowtransmits the digits for operating the call indieating signal. Theimpulse trains transmitted are received by relay S and are repeated bycontact s to relay SI in Fig. 2A. 'I'he setting .of the devices(switches D| and D2) for operating the call indicating signal takesplace in the manner described.

When the wanted party perceives the signal he proceeds to the nearesttelephone equipment and as already described causes the switch MW inFig. 2A to be set on the line to the station from which he has repliedby transmitting a characterizing digit. After this setting has beeneffected the following connection is established: from station Tnl overthe public exchange switch AW, enquiry line lill/I Il in Figs. 1A, 1Band 2A, over the switches SW and MW in Fig. 2A and line- 64/65 in Figs.2A, 1B and 1A to the station T112 from which the wanted party hasreplied.

It is possible for the subscriber who has replied from station Tn2 totake over the exchange call. For this purpose he has to operate the keyTa2. This energizes the differential relay X2 in Fig. 2A which isdisposed in the feeding circuit. 'Ihe relay X2 opens contact H312 andcloses contact ll42. The following circuit is established for relay RI:positive, contacts |5c|, H412, winding II of relay RI and negative.Relay RI closes contact Il Gal. When the subscriber releases the keyrelay X2 falls back. Contact ||4x2 opens and contact H312 closes. RelayRI on account of its slow operating features holds contact ||6r closedfor a moment so that the following circuit obtains: positive, contacts||5c|, H332, ||6r|, wiper e of switch SW, lead in Figs. 2A, 1B and 1A,contact H82, winding I of relay U and negative. Relay U is energizedtransitorily in the last mentioned circuit. Relay U opens contact 19uand closes contact IISu. Relay CI releases. Relay AB energizes. Therelease of relay Cl establishes the following locking circuit for delayU: positive, contacts ci and I'Ib winding II of relay U, contact |2011.and negative. Relay U maintains the feeding bridge. relay S energizedover contact |2|u so that this relay is not deenergzed by the opening oicontacts 82c| and 83cl. The release of relay Cl breaks the circuit forrelays Y and Z at contact I||2c|. Relays Y and Z restore their contactsto normal. The opening of contacts Illy and Illu and the closing ofcontacts |001 and lllly promotes the switching over from the enquiryline Ill/I on to the public exchange line AL. Through the energizing oi'relay U relay R is operated over: positive, contacts el and IIb,windings 11 and III of relay R, contact |2lu and negative. Relay Rcloses contact |2|r so that its winding II is short-circuited and it isaccordingly rendered slow-to-release. It also closes contact '|41'.'I'he public exchange switch AW is advanced by the rotary magnet DAW.The stepping continues until the following circuit is established:positive, contact |2'Ib, contact lir, winding In of relay Ci, wiper d,of .the public exchange switch AW, lead Il in Figs. 1A, 1B and 2A, wiperd of switch MW, contacts I22r2 and |23c3, winding I of relay Tr, contactI2lr| and |2512, wiper d of switch SW, lead ||2 in Figs, 2A, 1B and 1A,contacts |261' and |21ab, resistance Wl and negative. By opening contact16c| relay CI brings the public exchange switch AW to rest. The exchangeswitch is thus set on the speaking leads 64 and 85 associated withstation Tn2. 'I'hus the subscriber who has replied from station Tn! isconnected to the public exchange line over the switch AW.

In the testing circuit for setting the public exchange switch AW on theline associated with station Tn2 relay Tr in Fig. 2A is also energid. Atcontact iltr breaks the circuit over wiper c of switch SW. Relay C2releases. It breaks the circuit for relay SI at contacts |9c2 and 20c2.

Relay Sl releases and causes relay VI to release l by opening contact233|. VRelays C2, SI and VI in their deenergized condition restore tonormal the devices of the-call indicating system which have been used inthe manner already described.

As may be seen from the preceding description a subscriber who has beensought over the en- Vquiry devices of the telephone system can cause aswitch MW associated with the call indicating system to be set on theline of the station from which he replies by dialling a characteristictending thereto, special control lines, and means for extendingconnections from calling or answering telephone lines to any one of saidlines, a code calling system including first and second line ilnders,said finders having access to said telephone lines, signalling meanslocated at points common to said stations, means operated when aconnection is extended under control of a calling line to one of thespecial control lines for causing said first line finder to seize thecalling line and extend a connection from said calling line to saidsecond line ilnder, means for causing the extended connection to bereleased responsive to said seizure, means controlled by the callingline through said first line finder for operating said means inaccordance with a predetermined code to signal a particular party, meansoperated when a connection is extended under control of an answeringline to another one o f said special control lines for causing 1I *lsaid second line finder to seize the answering line,

'and means for causing said last extended connec tion to be releasedresponsive to said last seizure.

. v2. In a signalling system, connector switches, a' plurality of lineshaving access to 'said switches, special positions` for said connectorswitches,

, means responsive to a call over any one of said said lines, meansresponsive to said operation of the connector for causing said linefinder to seize said one line, and means responsive to said last seizurefor causing the operated connector switch to be released.

3. In a system as claimed in claim 2, means responsive to a call overany other of said lines for seizing one of said connectors, meansresponsive to impulses over said other line for operating said lastconnector to another one of said special positions, a second line finderhaving access to said line and associated with the said firstlinefinder, means responsive to said operation of said last connectorfor causing the second line finder to seize said other line, and meansresponsive to said last seizure for causing said last operated connectorswitch to be released, whereby said oneline and said other line-areassociated via said first line finder and said secondA line finder.

,4. In an automatic telephone system comprising a series of switchesincluding a connector switch, a pluralitvof lines having access to saidconnector switch, a special position for said connector switch, a linefinder havingV access to said lines, a trunk line terminating in saidline finder, means responsive to a call over any of said lines forseizing one of said connectors, means responsive to impulses over saidonefline for operating the connector to said special position, meansresponsive to the operation of the connector to said special positionfor causing said line finder to seize said one line and means responsiveto said last seizure for causing said connector switch to be released.

5. In an automatic telephone system, a plurality of stations associatedwith a code calling system, signalling means common to said stations,means for extending a connection from a calling one of said stations toanother station or to said signalling means, a trunk line, means forcausing an incoming call over said trunk to be extended directly to aparticular station, means controlled from Vsaid particular station forholding the trunk and for operating said signalling means to signal aparticular called party, means lwhereby the called party may answer thesignal from any one of said stations through the second-named means, andmeans controlled from the answering station for causing said laststation to be connected with the trunk call independent of thesecond-named means. o

6. In a telephone system, subscribers substations and lines therefor,junction equipment having access to said lines, switching apparatushaving access to said junction equipment, means at a plurality ofstations controlled by subscribers thereat for seizing certain of saidswitching apparatus and for controlling said certain apparatus to causesaid junction equipment to seize the lines of those stations, and meansresponsive to the seizure of each line for causing the certain apparatusseized and controlled thereover to be released, said junction equipmentbeing thus associated with said plurality of stations concurrently andeffective to join in a connection the lines thereof.

7. In a telephone system, subscribers' stations and lines therefor, alink circuit including a plurality of line finder switches each havingaccess to' said lines, a plurality of seizing paths for said link, otherlinks having access both to said lines and also to said first link,means responsive to a call over any of said lines for causing one ofsaid other links to be associated with the calling line, and means forcontrolling said one link to seize said rst link over one of said paths,one of the line finders effective responsive to saidseizure to seize thecalling line and to cause said one link to be disassociated therefrom,and means at another calling station for controlling one of said otherlinks to seize said first link over another path, whereupon said firstlink is eifective to seize the line of the other calling station, tocause said last-mentioned one link to be released, and to join thecalling subscribers in a connection.

8. In a telephone system, subscribers stations v'and lines therefor,switching equipment for extending calls of a particular character, otherswitching equipment for extending calls of a. different character, meansresponsive to a call over any of said lines for associating said rstswitching equipment withv the calling line, and means at the. callingstation for thereafter controlling said first switching equipment eitherto extend a call of'said particular character or to seize said otherswitching equipment, said other switchingA equipment effective if soseized to associate itself with the calling line and thereby cause saidrst switching equipment tobe released.

9, In a telephone system, subscribers stations and lines therefor,switching equipment for extending a particular class of calls, switchingequipment for extending each of a plurality of other classes of calls,means responsive to a calling condition on any of the lines for causingsaid first switching equipment to be associated with the calling line,and means at the calling station for thereafter controlling said firstswitching equipment either to extend a call of said particular class'orto seize the proper switching equipment for extending another class ofcall, the other switching equipment eifectiveif so seized to associateitself withthe calling line and thereby cause said first switchingequipment to be released.

10. In a telephone system, subscribers stations and lines therefor,switching equipment for extending calls between said lines, a signallingmeans and other switching equipment associated therewith, meansresponsive to a calling condition on any of said lines for associatingcertain of said first switching equipment with the calling line, meansat the calling station for thereafter controlling said certain switchingequipment either to extend a call to another station or to seize saidother switching equipment, said other switching equipment effective ifso seized to associate itself with the calling line and to thereby causecertain switching equipment to be released,

Asaid other switching equipment then controllable by the subscriber atthe calling station to actuate said signalling means, means for placinga calling condition on the line of any other station to respond to thesignal and, when certain of said first switching equipment is associatedwith the responding line, for controlling said certain equipment tocause said other equipment to associate itself with the responding line,whereupon said certain equipment is released and said other switchingequipment is effective to complete a connection between the calling andresponding lines.

11. In a telephone system, subscribers stations and lines therefor, aninquiry line, switching equipment having access to said lines andeifective to respond to a calling condition upon any of the lines. asignalling means and other switching equipment associated therewith, atrunk line, means for connecting a subscribers line to said trunk line,said last means controllable by the subscriber to cause said trunk lineto be held and to associate the subsribers line with the inquiry line toestablish a calling condition thereon for the initiation of a call toanother subscriber, means responsive to the calling condition on theinquiry line for associating certain of said rst switching equipmentwith the inquiry line, means at the calling station for thereaftercontrolling said certain switching equipment either to extend a call toanother station or to seize said other switching equipment, said otherswitching equipment effective if so seized to associate itself with theinquiry line and thereby cause said certain switching equipment to bereleased, said other switching equipment then controllable by thesubscriber at the said calling station to actuate said signalling means,means for placing a calling condition on the line of any other stationto respond to the signal and, when certain of said first switchingequipment is associated with the responding line. for controlling saidcertain equipment to cause said other switching equipment to associateitself with the responding line, whereupon said certain equipment isreleased and said other switching equipment is effective to associatethe inquiry line and the responding line. thus completing a connectionbetween the calling and the desired subscribers.

12. In a telephone system, subscribers stations and lines therefor, aninquiry line, a trunk line, a switch terminating said trunk line andhaving access over its wipers to said subscribers lines, means includingsaid switch for completing a connection between one of the subscriberslines and the trunk line, means at the subscribers stanon forcontrolling said switch to hom seid trunk line and to seize said inquiryline, thereby to initiate an inquiry connection including saidsubscribers line, said wipers and said inquiry line, switching meansaccessible to said inquiry line for completing the inquiry connectionbetween said one subscribers line and another of said subscribers lines,and means at the other subscribers station for causing said wipers to bemoved from said one subscribers line to said other subscribers line andfor causing said inquiry line and said switching means accessiblethereto to be released, whereby said trunk connection is transferred tosaid other subscribers line and said one subscribers line is released.

WALTER PFAFF.

